This invention relates to systems for coupling a point remote from a particular telephone instrument of a telephone network to such telephone instrument and more particularly to an interface for coupling a particular telephone instrument to a wireless voice operated transceiver with no direct electrical connection between the interface and the telephone instrument and no modification of the wireless voice operated transceiver.
A wide variety of systems for coupling a remote point to a telephone network by means of a wireless radio link have been proposed. Such systems have either required a specially built or wired telephone instrument to enable direct electrical connections to the telephone network in conformity with telephone company regulations or a specially constructed wireless communication system, or both, particularly where the system is designed to operate without human intervention at the telephone instrument.
It is an object of this invention to provide a method of and means for interfacing between a telephone instrument and a conventional wireless communication system to enable coupling of the telephone instrument to a remote point without human intervention at the telephone instrument and without direct electrical connection to the telephone instrument or use of a specially constructed wireless communication system.
In the prior art, elaborate wireless communication systems were proposed involving special transmitters and receivers as well as special oscillator circuits and solenoids which not only separated the incoming and outgoing signals of the wireless system but also enabled the control of the telephone instrument from the remote point. Such wireless systems had to be specially fabricated and were thus too expensive for use in many applications particularly where all that is desired is the coupling of an incoming call on the telephone instrument to a remote point.
It is a further object of this invention to provide a method of and means for interfacing between a telephone instrument and any commercially available wireless communication system including wireless transceivers at least one of which is voice actuated.
Although simplification of the prior art systems to eliminate control of the telephone from the remote point has been proposed heretofore, none of the prior art systems have made adequate allowance for the fact that the mouthpiece and earpiece of the telephone instrument are electrically connected in such a way that a person speaking into the mouthpiece will hear his own voice in the earpiece of the instrument. Thus, if the telephone instrument is coupled to a conventional wireless transceiver system, which would necessarily require that the transceiver located at the telephone handset be voice actuated in order to provide automatic operation, it will be seen that a signal from the remote point applied to the mouthpiece of the telephone instrument will also generate a corresponding signal at the earpiece of the instrument tending to actuate the transmitting mode of the wireless transceiver located at the instrument thereby interfering with the desired operation of the wireless communication system.
Thus, it is another object of this invention to provide a method of and means for interfacing between a telephone instrument and a conventional wireless communication system including a voice actuated transceiver at the telephone instrument which will avoid interference between the incoming and outgoing signals of the voice actuated transceiver.
Furthermore, the prior art has required complicated circuitry for disconnecting the telephone instrument from the telephone network upon termination of a particular conversation over the system. Such circuits have either required some sort of control originating at the remote point or have included complicated circuitry for detecting the cessation of the conversation and thereafter disconnecting the telephone instrument from the telephone network. It will be understood that the provision of control at the remote point would require modification of commercial wireless communication systems. It will also be understood that circuitry for detecting cessation of actual conversation is subject to inaccurate operation due to noise in the communication system or unexpected delays in the conversation.
It is a still further object of this invention to provide a method of and means for interfacing between a telephone instrument and a wireless communication system in which the telephone instrument is disconnected from the telephone network in response to a signal generated by the telephone instrument itself in normal operation.
A particular object of the invention is to provide means which allows any microphone (supplied with a transceiver) to be efficiently coupled (i.e. acoustic impedance matched) to the apparatus and further this means may include a plurality of microphones and speakers for additional speech or signalling control functions, whereby this means is to be called "audio mixing means", in contradistinction to the "audio transducer means" which comprises the telephone handset coupler itself which uses a specific microphone-speaker set acoustically coupled to the telephone handset.